I usually like to imagine a blockchain as a ledger, specifically, a public ledger containing lists of transactions. Since we are coining the words block and chain, it means that records are usually grouped in a specific manner, where each group contains a hash of the previous block, a timestamp and transaction data. Meaning that every block is linked to the next and records in each block can never be altered as this would shatter the integrity of the chain since every block contains a hash to specific data.